# US 12,761,295 B2 · Magnetoresistive element having an out-of-plane sensitivity axis and having reduced hysteresis and increased working field range

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- Number: US 12,761,295 B2
- Document ID: US12761295B2
- Status: Granted
- Kind: B2
- Application number: 19/156,467
- Filed: 2024-02-13
- Published: 2026-08-06
- Granted: 2026-10-13
- Earliest claimed: 2023-02-17
- Assignees: Allegro MicroSystems, LLC
- Applicants: Allegro MicroSystems, LLC
- Inventors: Salim Dounia; Andrey Timopheev; Nikita Strelkov
- Web page: https://patentgrep.com/patent/US12761295B2

## CPC

- G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)}
- G01R 33/0017: {Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields}
- G01R 33/0052: {Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips (devices based on galvano-magnetic effect or the like H10N50/85)}
- G01R 33/098: {comprising tunnel junctions, e.g. tunnel magnetoresistance sensors}
- H10N 50/10: Magnetoresistive devices
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Magnetoresistive element (20) for sensing an external magnetic field, comprising a tunnel barrier layer (22) sandwiched between a ferromagnetic reference layer (21) having a pinned reference magnetization (210), and a ferromagnetic sense layer (23) having a sense magnetization (230), wherein the reference, tunnel barrier, and sense layers (21, 22, 23) are stacked perpendicular to a layer plane (PL) thereof. The reference magnetization (210) is oriented substantially perpendicular to the layer plane (PL), and the sense magnetization (230) is oriented substantially parallel to the layer plane (PL). At least the sense layer (23) has an annular cross-section in the layer plane (PL), with an inner diameter (Dint) and an outer diameter (Dout). The sense magnetization (230) has a closed flux path configuration that is orientable either in the clockwise or counterclockwise direction. The inner diameter (Dintt) is larger than 300 nm, and a difference between the inner and outer diameters (Dint, Dout) is greater than 150 nm.

## Claims

### Claim 1

A magnetoresistive element for sensing an external magnetic field, comprising:
a tunnel barrier layer sandwiched between a ferromagnetic reference layer having a pinned reference magnetization, and a ferromagnetic sense layer having a sense magnetization that can be freely oriented in the external magnetic field;
wherein the reference, tunnel barrier, and sense layers are stacked perpendicular to a layer plane thereof;
wherein the reference magnetization is oriented substantially perpendicular to the layer plane, and the sense magnetization is oriented substantially parallel to the layer plane;
wherein at least a portion of the magnetoresistive element has an annular cross-section in the layer plane forming an interior part and an exterior part of said at least a portion, the interior part having an inner diameter and the exterior part having an outer diameter;
wherein said at least a portion comprises the sense layer, and wherein the sense magnetization has a closed flux path configuration being orientable either in the clockwise or counterclockwise direction; and wherein the inner diameter being larger than 300 nm, and a difference between the inner and outer diameters is greater than 150 nm.

### Claim 2 (depends on 1)

The magnetoresistive element according to claim 1, wherein said at least a portion further comprises the reference layer.

### Claim 3 (depends on 1)

The magnetoresistive element according to claim 1, wherein said at least a portion further comprises the tunnel barrier layer.

### Claim 4 (depends on 1)

The magnetoresistive element according to claim 1, wherein the outer diameter is between 500 nm and 5000 nm.

### Claim 5 (depends on 1)

The magnetoresistive element according to claim 1, wherein the sense layer has a thickness greater than 15 nm.

### Claim 6 (depends on 1)

The magnetoresistive element according to claim 1, wherein the aspect ratio of the thickness to diameter of the sense layer is between 0.005 and 2.

### Claim 7 (depends on 1)

The magnetoresistive element according to claim 1, wherein the resistance-area-product (RA) of the magnetoresistive element is higher than 50 ohm·μm2.

### Claim 8 (depends on 1)

The magnetoresistive element according to claim 1, wherein the interior part has a substantially circular shape.

### Claim 9 (depends on 1)

The magnetoresistive element according to claim 1, wherein the interior part has a substantially elliptical shape.

### Claim 10 (depends on 1)

The magnetoresistive element according to claim 1, wherein the interior part is nonconcentric with the exterior part.

### Claim 11 (depends on 1)

A magnetoresistive sensor device comprising a plurality of the magnetoresistive elements according to claim 1, wherein the magnetoresistive elements are electrically connected in series or in parallel.